U.S. patent number 9,850,397 [Application Number 14/777,038] was granted by the patent office on 2017-12-26 for plastic film.
This patent grant is currently assigned to LG CHEM, LTD.. The grantee listed for this patent is LG CHEM, LTD.. Invention is credited to Yeong Rae Chang, Sung Don Hong, Joon Koo Kang, Heon Kim, Hye Min Kim.
United States Patent |
9,850,397 |
Kang , et al. |
December 26, 2017 |
Plastic film
Abstract
The present invention relates to a plastic film. More
particularly, the present invention relates to a plastic film which
exhibits high hardness, self-healing property and excellent
processability. The plastic film of the present invention exhibits
high hardness, self-healing property, scratch resistance, high
transparency, durability, light resistance, light transmittance or
the like, and thus can be applied to various fields.
Inventors: |
Kang; Joon Koo (Daejeon,
KR), Chang; Yeong Rae (Daejeon, KR), Hong;
Sung Don (Daejeon, KR), Kim; Heon (Daejeon,
KR), Kim; Hye Min (Daejeon, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG CHEM, LTD. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG CHEM, LTD. (Seoul,
KR)
|
Family
ID: |
51757843 |
Appl.
No.: |
14/777,038 |
Filed: |
March 13, 2014 |
PCT
Filed: |
March 13, 2014 |
PCT No.: |
PCT/KR2014/002125 |
371(c)(1),(2),(4) Date: |
September 15, 2015 |
PCT
Pub. No.: |
WO2014/142581 |
PCT
Pub. Date: |
September 18, 2014 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20160032137 A1 |
Feb 4, 2016 |
|
Foreign Application Priority Data
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|
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Mar 15, 2013 [KR] |
|
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10-2013-0028138 |
Mar 15, 2013 [KR] |
|
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10-2013-0028139 |
Mar 12, 2014 [KR] |
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10-2014-0029030 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08J
3/243 (20130101); C08J 7/0427 (20200101); C08K
3/36 (20130101); C08J 3/24 (20130101); C09D
135/02 (20130101); C09D 7/40 (20180101); C08J
7/046 (20200101); C09D 133/14 (20130101); C09D
133/14 (20130101); C08K 3/00 (20130101); C08J
2400/24 (20130101); C08J 2400/208 (20130101); C08J
2400/21 (20130101); C08J 2451/00 (20130101); C08J
2433/04 (20130101) |
Current International
Class: |
C08J
3/24 (20060101); C08J 7/04 (20060101); C09D
7/12 (20060101); C08K 3/36 (20060101); C09D
135/02 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102105515 |
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Jun 2011 |
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102317384 |
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CN |
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102781986 |
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CN |
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2 840 107 |
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EP |
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2 843 008 |
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EP |
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2 857 440 |
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EP |
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2 865 707 |
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2 873 692 |
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EP |
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2897078 |
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Mar 1993 |
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JP |
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2004-035599 |
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2008-197662 |
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JP |
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2009-204725 |
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JP |
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2010-53231 |
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JP |
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2010-121013 |
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JP |
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2010-280832 |
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JP |
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2011-74135 |
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JP |
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2012-030532 |
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Feb 2012 |
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4911474 |
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Apr 2012 |
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JP |
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2012-180487 |
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Sep 2012 |
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JP |
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10-2007-0096329 |
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Oct 2007 |
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KR |
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10-2008-0055698 |
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Jun 2008 |
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KR |
|
10-0916171 |
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Sep 2009 |
|
KR |
|
10-2010-0028648 |
|
Mar 2010 |
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KR |
|
10-2010-0041992 |
|
Apr 2010 |
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KR |
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10-2011-0119704 |
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Nov 2011 |
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KR |
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10-1127952 |
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Mar 2012 |
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KR |
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10-2012-0093088 |
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Aug 2012 |
|
KR |
|
2007/142142 |
|
Dec 2007 |
|
WO |
|
2012/111947 |
|
Aug 2012 |
|
WO |
|
Other References
Extended European Search Report issued for European Patent
Application No. 14763678.1 date Sep. 22, 2016, 9 pages. cited by
applicant .
International Search Report issued in International Application No.
PCT/KR2014/002125 dated Jun. 26, 2014, 2 pages. cited by
applicant.
|
Primary Examiner: Niland; Patrick
Attorney, Agent or Firm: Rothwell, Figg, Ernst &
Manbeck, P.C.
Claims
What is claimed is:
1. A plastic film, comprising: a support substrate; and a coating
layer formed on at least one side of the support substrate, wherein
the coating layer includes: (i) a crosslinked copolymer, in which a
tri- to hexafunctional acrylate-based monomer and a caprolactone
group-containing multifunctional acrylate-based compound are
copolymerized at a weight ratio of 5:5 to 8:2, and (ii) an
inorganic fine particle, which is dispersed in the crosslinked
copolymer, wherein the caprolactone group-containing
multifunctional acrylate-based compound is polyrotaxane.
2. The plastic film of claim 1, wherein the polyrotaxane includes a
macrocycle, to which a caprolactone group having an acrylate-based
compound introduced at the end thereof binds; a linear molecule
penetrating the macrocycle; and blocking groups arranged at both
ends of the linear molecule to prevent the macrocycle from
escaping.
3. The plastic film of claim 2, wherein the macrocycle includes one
or more selected from the group consisting of .alpha.-cyclodextrin,
.beta.-cyclodextrin, and .gamma.-cyclodextrin, and wherein the
linear molecule is a polyoxyalkylene compound or a polycaprolactone
group.
4. The plastic film of claim 2, wherein the blocking group includes
one or more functional groups selected from the group consisting of
dinitrophenyl, cyclodextrin, adamantane, trityl, fluorescein, and
pyrene groups.
5. The plastic film of claim 1, comprising 50 to 90 parts by weight
of the crosslinked copolymer and 10 to 50 parts by weight of the
inorganic fine particle when the total weight of the coating layer
is regarded as 100 parts by weight.
6. The plastic film of claim 1, wherein the coating layer further
includes a thermosetting resin.
7. The plastic film of claim 6, wherein the thermosetting resin is
a thermoset product of a prepolymer composition including a
polyester-based polyurethane oligomer, a polyol, and a
polyisocyanate.
8. The plastic film of claim 7, comprising 10 to 40% by weight of
the polyester-based polyurethane oligomer, 5 to 30% by weight of
the polyol, and 50 to 80% by weight of the polyisocyanate, based on
the total weight of the thermosetting prepolymer composition.
9. The plastic film of claim 7, wherein the polyol includes one or
more selected from the group consisting of polyethylene glycol
polyol, polycarprolactone polyol, polyester polyol, polyether
polyol, polyacryl polyol, and polycarbonate polyoldiol.
10. The plastic film of claim 7, wherein the polyisocyanate is one
or more selected from the group consisting of 1,4-tetramethylene
diisocyanate, 1,6-hexamethylene diisocyanate, 1,4-cyclohexyl
diisocyanate, isophorone diisocyanate, .alpha.,.alpha.-xylylene
diisocyanate, 4,4'-dimethylmethane diisocyante, 1,3-phenylene
diisocyanate, and toluene diisocyanate, or polyisocyanate
polymerized from dimers or trimers thereof.
11. The plastic film of claim 6, comprising the crosslinked
copolymer and the thermosetting resin at a weight ratio of 1:0.01
to 1:3.
12. The plastic film of claim 6, comprising 40 to 80 parts by
weight of the crosslinked copolymer, 5 to 50 parts by weight of the
thermosetting resin, and 5 to 40 parts by weight of the inorganic
fine particle, based on 100 parts by weight of the coating
layer.
13. The plastic film of claim 1, wherein the tri- to hexafunctional
acrylate-based monomer includes one or more selected from the group
consisting of trimethylolpropane triacrylate (TMPTA),
trimethylolpropane ethoxy triacrylate (TMPEOTA),
glycerin-propoxylated triacrylate (GPTA), pentaerythritol
tetraacrylate (PETA), and dipentaerythritol hexaacrylate
(DPHA).
14. The plastic film of claim 1, wherein the thickness of the
coating layer is 50 to 300 .mu.m.
15. The plastic film of claim 1, wherein the plastic film does not
crack even after a steel bead weighing 22 g is freely dropped ten
times from a height of 50 cm thereto.
16. The plastic film of claim 1, wherein the coating layer has a
pencil hardness of 6H or more under a load of 1 kg.
17. The plastic film of claim 1, wherein the plastic film has
self-healing capability.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a 35 U.S.C. .sctn.371 National Phase Entry
Application from PCT/KR2014/002125, filed Mar. 13, 2014, and
designating the United States, which claims priority under 35
U.S.C. .sctn.119 to Korean Patent Application No. 10-2013-0028138
filed on Mar. 15, 2013, to Korean Patent Application No.
10-2013-0028139 filed on Mar. 15, 2013, and to Korean Patent
Application No. 10-2014-0029030 filed on Mar. 12, 2014, which are
incorporated herein by reference in their entireties.
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a plastic film. More particularly,
the present invention relates to a plastic film which exhibits high
hardness, impact resistance, self-healing property and excellent
processability.
This application claims the benefit of Korean Patent Application
No. 10-2013-0028138, filed on Mar. 15, 2013, Korean Patent
Application No. 10-2013-0028139, filed on Mar. 15, 2013, and Korean
Patent Application No. 10-2014-0029030, filed on Mar. 12, 2014,
which are all hereby incorporated by reference in their entireties
into this application.
(b) Description of the Related Art
With the advance of mobile appliances such as smart phones, tablet
PCs or the like, substrates for displays have recently been
required to become lighter and slimmer. Display windows or front
panels of such mobile appliances are generally made of glass or
reinforced glass both of which have excellent mechanical
properties. However, glass suffers from the disadvantage that its
own weight makes mobile appliances heavy and it is easily broken by
an external impact.
As an alternative to glass, plastic resins have been studied. The
plastic resin films are light in weight and resistant to impact,
and thus are consistent with the trend of pursuing lighter mobile
appliances. Particularly, to achieve a film with properties of high
hardness and wear resistance, it is proposed to utilize a film in
which a support substrate is coated with a coating layer.
Increasing the thickness of the coating layer is considered as an
approach to improving the surface hardness thereof. The coating
layer should be of a predetermined thickness to ensure the surface
hardness sufficient as the alternative to glass. However, as the
coating layer increases in thickness, the surface hardness thereof
may become higher, but the coating layer is more prone to setting
shrinkage which leads to wrinkling or curling with the concomitant
production of cracks or exfoliations, and thus the coating layers
are difficult to employ in practice.
Recently, some methods have been proposed for conferring a high
hardness on hard coating films, without the problems of cracking
and setting shrinkage-induced curling.
Korean Patent Publication No. 2010-0041992 discloses a plastic film
composition, free of monomers, including a binder resin based on
ultraviolet-curable polyurethane acrylate-based oligomers. However,
this plastic film has a pencil hardness of about 3H, and thus the
strength thereof is not sufficient to be a substitute for glass
panels for displays.
Meanwhile, studies on coating materials having self-healing
capability are actively progressing because they do not require an
additional coating or repair process even when the surface is
damaged, and are extremely favorable for appearance and performance
maintenance of products. As a result of these studies, compositions
containing UV curable compositions using self-healing oligomers
have been suggested, but coating materials obtained from the
compositions have problems of insufficient surface hardness and
self-healing capability.
SUMMARY OF THE INVENTION
In order to solve the above problems, the present invention
provides a plastic film which exhibits high hardness, scratch
resistance and excellent mechanical properties, and also excellent
processability and self-healing property, without the problems of
curling, warping or cracking.
In order to solve the above problems, the present invention
provides a plastic film, including:
a support substrate; and
a coating layer formed on at least one side of the support
substrate, including a crosslinked copolymer, in which a tri- to
hexafunctional acrylate-based monomer and a caprolactone
group-containing multifunctional acrylate-based compound are
copolymerized at a weight ratio of 5:5 to 8:2, and an inorganic
fine particle dispersed in the crosslinked copolymer.
The plastic film of the present invention exhibits high hardness,
impact resistance, self-healing property, scratch resistance, and
high transparency, and is superior in terms of processability to be
less prone to curling or cracking. The plastic film can be usefully
applied to mobile appliances, display instruments, and front panels
and display windows of various instruments as an alternative to a
cover plate made of glass or reinforced glass.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The plastic film of the present invention includes
a support substrate; and
a coating layer formed on at least one side of the support
substrate, including a crosslinked copolymer, in which a tri- to
hexafunctional acrylate-based monomer and a caprolactone
group-containing multifunctional acrylate-based compound are
copolymerized at a weight ratio of 5:5 to 8:2, and an inorganic
fine particle dispersed in the crosslinked copolymer.
As used herein, the term "first", "second", etc. is employed only
to describe various elements, and is intended to discriminate one
element from another.
All of the terms used in the specification are taken only to
illustrate embodiments, and are not intended to limit the present
invention. The singular forms include plural references unless the
context clearly dictates otherwise. It is to be noticed that the
term "include", "including", "having", etc., as used herein, is to
be interpreted as specifying the presence of the stated features,
steps, components, or combinations thereof, but does not preclude
the presence or addition of one or more other features, steps,
components, or combinations thereof.
Additionally, the word "on" or "above", as used in the context of
formation of one element, means pertaining to the direct formation
of one element on another element or the additional formation of
one element between layers or on a subject or substrate.
The present invention may be modified in various ways and include
several embodiments. Specific embodiments are illustrated and
described in detail below. The present invention, however, should
not be construed as limited to the exemplary embodiments set forth
herein but may include any modifications, equivalents or
alternatives within the spirit and scope of the present
invention.
Hereinafter, the plastic film of the present invention will be
described in more detail.
According to one aspect, the present invention provides a plastic
film including a support substrate; and a coating layer formed on
at least one side of the support substrate, the coating layer
including a crosslinked copolymer, in which a tri- to
hexafunctional acrylate-based monomer and a caprolactone
group-containing multifunctional acrylate-based compound are
copolymerized at a weight ratio of 5:5 to 8:2, and an inorganic
fine particle dispersed in the crosslinked copolymer.
In the plastic film of the present invention, any typical plastic
resin, whether capable of being stretched or not, may be used for
the support substrate on which the coating layer is formed, without
particular limitations in the preparation method or the material
thereof, so long as it is transparent. More specifically, according
to one embodiment of the present invention, the support substrate
may be a film including, for example, polyester such as
polyethyleneterephthalate (PET), polyethylene such as ethylene
vinyl acetate (EVA), a cyclic olefin polymer (COP), a cyclic olefin
copolymer (COC), polyacrylate (PAC), polycarbonate (PC),
polyethylene (PE), polymethylmethacrylate (PMMA),
polyetheretherketone (PEEK), polyethylenenaphthalate (PEN),
polyetherimide (PEI), polyimide (PI), triacetylcellulose (TAC), MMA
(methyl methacrylate), a fluoro-polymer or the like. The support
substrate may be a single layer structure, or if necessary, may be
a multilayer structure including two or more substrates composed of
the same or different materials, but is not particularly limited
thereto.
According to one embodiment of the present invention, the support
substrate may be a multilayered substrate made of
polyethyleneterephthalate (PET) or a multilayered substrate made of
co-extruded polymethylmethacrylate (PMMA)/polycarbonate (PC).
Further, according to one embodiment of the present invention, the
support substrate may be a substrate including a copolymer of
polymethylmethacrylate (PMMA) and polycarbonate (PC).
The thickness of the support substrate is not particularly limited,
but the support substrate having a thickness of approximately 30 to
approximately 1,200 .mu.m, or approximately 50 to approximately 800
.mu.m may be used.
The plastic film of the present invention includes a coating layer
which is formed on at least one side of the support substrate.
The coating layer includes a crosslinked copolymer, in which a tri-
to hexafunctional acrylate-based monomer and a caprolactone
group-containing multifunctional acrylate-based compound are
copolymerized at a weight ratio of 5:5 to 8:2, and an inorganic
fine particle dispersed in the crosslinked copolymer.
The term "acrylate-based," throughout the present specification, is
intended to encompass acrylate, methacrylate, and derivatives
thereof introduced with various substituents.
The tri- to hexafunctional acrylate-based monomer may be
trimethylolpropane triacrylate (TMPTA), trimethylolpropane ethoxy
triacrylate (TMPEOTA), glycerin-propoxylated triacrylate (GPTA),
pentaerythritol tetraacrylate (PETA), dipentaerythritol
hexaacrylate (DPHA) or the like. These tri- to hexafunctional
acrylate-based monomers may be used alone or in combination of
different types thereof.
As used herein, the term "caprolactone group-containing
multifunctional acrylate-based compound" means a monomer compound,
an oligomer or a polymer material, which includes a di- or
multifunctional acrylate group crosslinkable with the tri- to
hexafunctional acrylate-based monomer and also includes
caprolactone or a repeating unit derived therefrom in the
molecule.
The crosslinked copolymer of the caprolactone group-containing
multifunctional acrylate-based compound is able to exhibit
excellent physical properties such as flexibility, elasticity,
impact resistance, durability or the like, and also self-healing
capability against an external impact. Therefore, the plastic film
including the crosslinked copolymer which is prepared by
crosslinking polymerization of the caprolactone group-containing
multifunctional acrylate-based compound and the tri- to
hexafunctional acrylate-based monomer secures mechanical properties
such as high scratch resistance, high hardness, wear resistance or
the like, and also high elasticity or elastic recovery, and
achieves excellent self-healing capability against scratch or
external damage, with minimal curling or cracking occurrence.
As used herein, the term "self-healing" means a property of
recovering the original condition within a predetermined time,
without an additional coating or repair process even when the
surface of the coating layer is damaged by scratch, etc., and it
can be evaluated by measuring a time to recover from a scratch
after rubbing the surface of the coating layer with a copper brush,
when observed with the naked eye.
According to one embodiment of the present invention, the
caprolactone group-containing multifunctional acrylate-based
compound may include, for example, a polycaprolactone
acrylate-based polymer or polyrotaxane.
Generally, polyrotaxane means a structurally interlocked compound
consisting of a dumbbell shaped molecule and a macrocycle, in which
the dumbbell shaped molecule includes a certain linear molecule and
blocking groups arranged at both ends of the linear molecule, the
linear molecule penetrates the inside of the macrocycle, and the
macrocycle may move along the linear molecule and be prevented from
escaping by the blocking groups.
According to one embodiment of the present invention, the
polyrotaxane is characterized in that a caprolactone compound or a
repeating unit compound derived therefrom binds to the macrocycle,
and an acrylate-based compound binds to the end of the caprolactone
compound.
Specifically, the acrylate-based compound may directly bond to the
end of the caprolactone compound, or may bind via a urethane bond
(--NH--CO--O--), an ether bond (--O--), a thioester bond
(--S--CO--O--), or an ester bond (--CO--O--). The type of the
functional group that mediates a bond between the acrylate-based
compound and the caprolactone compound may be determined according
to the type of the functional groups respectively substituted in
the acrylate-based compound and the caprolactone compound, or the
type of the compound used in the reaction of the acrylate-based
compound and the caprolactone compound.
For example, if an acrylate-based compound including one or more of
an isocyanate group, a carboxyl group, a hydroxyl group, a thioate
group, or a halogen group is reacted with a macrocycle to which a
caprolactone compound binds, a direct bond, a urethane bond
(--NH--CO--O--), an ether bond (--O--), a thioester bond
(--S--CO--O--), or an ester bond (--CO--O--) may be formed.
Further, if a reaction product of the caprolactone-bonded
macrocycle with a compound including two or more of an isocyanate
group, a carboxyl group, a hydroxyl group, a thioate group, or a
halogen group is reacted with an acrylate-based compound including
one or more of a hydroxyl group or a carboxyl group, one or more of
a urethane bond (--NH--CO--O--), an ether bond (--O--), a thioester
bond (--S--CO--O--), or an ester bond (--CO--O--) may be
formed.
The acrylate-based compound may be a (meth)acryloylakyl compound, a
(meth)acryloylcycloakyl compound or a (meth)acryloylaryl compound,
to which one or more of an isocyanate group, a carboxyl group, a
thioate group, a hydroxyl group, or a halogen group bind at the
end.
Herein, a C1-12 linear or branched alkylene group may be included
in the (meth)acryloyl alkyl compound, a C4-20 cycloalkylene group
may be included in the (meth)acryloyl cycloalkyl compound, and a
C6-20 arylene group may be included in the (meth)acryloyl aryl
compound.
The macrocycle may include any macrocycle without particular
limitations as long as it has a sufficient size to penetrate or
surround the linear molecule, and it may include a functional group
such as a hydroxyl group, an amino group, a carboxyl group, a thiol
group, or an aldehyde group that may react with other polymers or
compounds. Specific examples of the macrocycle may include
.alpha.-cyclodextrin, .beta.-cyclodextrin, .gamma.-cyclodextrin, or
a mixture thereof.
The caprolactone compound binding to the macrocycle may directly
bind to the macrocycle, or may bind thereto via a C1-10 linear or
branched oxyalkylene group. The functional group that mediates the
bond may be determined according to the type of the functional
group substituted in the macrocycle or the caprolactone compound,
or the type of the compound used in the reaction of the macrocycle
and the caprolactone compound.
Meanwhile, the liner molecule may be any compound without
limitations as long as it has a molecular weight over certain level
and has a linear shape, but a polyalkylene-based compound or a
polycaprolactone group is preferably used. Specifically, a
polyoxyalkylene-based compound having a C1-8 oxyalkylene repeating
unit or a polycaprolactone group having a C3-10 lactone-based
repeating unit may be used.
Further, the linear molecule may have a weight average molecular
weight of approximately 1,000 to approximately 50,000 g/mol. If the
weight average molecular weight of the linear molecule is too low,
a coating layer prepared using the same may not have sufficient
mechanical properties or self-healing capability, and if the weight
average molecular weight is too high, compatibility of the prepared
coating layer may be lowered or the appearance or uniformity of the
material may be significantly lowered.
Meanwhile, the blocking group may be appropriately controlled
according to the property of the prepared polyrotaxane compound,
and for example, one or two or more selected from the group
consisting of dinitrophenyl, cyclodextrin, adamantane, trityl,
fluorescein, and pyrene groups may be used.
The polyrotaxane compound having the above structure may have a
weight average molecular weight of approximately 100,000 to
approximately 800,000 g/mol, approximately 200,000 to approximately
700,000 g/mol, and approximately 350,000 to approximately 650,000
g/mol. If the weight average molecular weight of the polyrotaxane
compound is too low, a coating layer prepared therefrom may not
have sufficient mechanical properties or self-healing capability,
and if the weight average molecular weight is too high, the
appearance or uniformity of the layer may be significantly
lowered.
Further, since the acrylate-based compound may be introduced at the
end of the macrocycle, the polyrotaxane compound may have a
relatively low OH value. That is, if only a caprolactone group
binds to the macrocycle, multiple hydroxyl (--OH) groups may exist
in the polyrotaxane molecule, but as the acrylate-based compound is
introduced at the end of the caprolactone group, the OH value of
the polyrotaxane compound may be lowered.
According to the plastic film of the present invention, the coating
layer includes a crosslinked copolymer which is formed by
crosslinking the caprolactone group-containing multifunctional
acrylate-based compound with the tri- to hexafunctional
acrylate-based monomer at a predetermined weight ratio. Therefore,
the coating layer is provided with high hardness and self-healing
capability, and secures excellent scratch resistance and impact
resistance by preventing damage due to an external impact.
The crosslinked copolymer is a crosslinked copolymer which is
formed by copolymerizing the tri- to hexafunctional acrylate-based
monomer and the caprolactone group-containing multifunctional
acrylate-based compound at a weight ratio of approximately 5:5 to
approximately 8:2, or approximately 6:4 to approximately 8:2, or
approximately 7:3 to approximately 8:2. If the content of the
caprolactone group-containing multifunctional acrylate-based
compound is too low beyond the above range, it is difficult to
achieve the self-healing effect. If the content of the caprolactone
group-containing multifunctional acrylate-based compound is too
high, hardness of the coating layer may be lowered. Therefore, the
crosslinked copolymer, which is formed by copolymerizing the tri-
to hexafunctional acrylate-based monomer and the caprolactone
group-containing multifunctional acrylate-based compound at the
above weight ratio, is included to achieve impact resistance,
scratch resistance, high hardness and the desired level of
self-healing capability.
In the plastic film of the present invention, the coating layer
includes the inorganic fine particles dispersed in the crosslinked
copolymer.
According to one embodiment of the present invention, the inorganic
fine particles may be an inorganic fine particle having a diameter
in the nanoscale. For example, they may have a diameter of
approximately 100 nm or less, or approximately 10 to 100 nm, or
approximately 10 to 50 nm. As the inorganic fine particles, for
example, silica particles, aluminum oxide particles, titanium oxide
particles, or zinc oxide particles may be employed.
The inorganic fine particles are included to further reinforce the
hardness of the plastic film.
According to one embodiment of the present invention, the coating
layer may include approximately 50 to approximately 90 parts by
weight of the crosslinked copolymer and approximately 10 to
approximately 50 parts by weight of the inorganic fine particle, or
approximately 60 to approximately 80 parts by weight of the
crosslinked copolymer and approximately 20 to approximately 40
parts by weight of the inorganic fine particle, when the total
weight of the coating layer is regarded as 100 parts by weight.
When the crosslinked copolymer and the inorganic fine particle are
included in the above range, a plastic film with excellent physical
properties can be formed.
According to one embodiment of the present invention, the coating
layer may further include a thermosetting resin.
Herein, the "thermosetting resin" means a thermosetting product
formed by thermosetting the components of the thermosetting
prepolymer composition including oligomers or polymers having
functional groups which are able to undergo crosslinking by
thermosetting.
According to one embodiment of the present invention, the
thermosetting prepolymer composition may include a polyester-based
polyurethane oligomer, a polyol, and a polyisocyanate. More
specifically, the thermosetting prepolymer composition may contain
approximately 10 to approximately 40% by weight of the
polyester-based polyurethane oligomer, approximately 5 to
approximately 30% by weight of the polyol, and approximately 50 to
approximately 80% by weight of the polyisocyanate, based on the
total weight of the solid components thereof.
According to one embodiment of the present invention, the
polyester-based polyurethane oligomer may be those having the
physical properties of a number average molecular weight of
approximately 1,000 to approximately 100,000 g/mol, a viscosity of
approximately 100 to approximately 3,000 cps when dissolved at a
concentration of 15% in cyclohexane, and Tg of -30 to 40.degree. C.
The polyester-based polyurethane oligomers with such physical
properties may be directly synthesized or may be commercially
purchased. The commercially available products may be exemplified
by ESTANE.RTM. 5701 TPU, ESTANE.RTM. 5703 TPU, ESTANE.RTM. 5707
TPU, ESTANE.RTM. 5708 TPU, ESTANE.RTM. 5713 TPU, ESTANE.RTM. 5714
TPU, ESTANE.RTM. 5715 TPU, ESTANE.RTM. 5719 TPU, or ESTANE.RTM.
5778 TPU, all from Noveon.
According to one embodiment of the present invention, the polyol
may have a number average molecular weight of approximately 1,000
to approximately 100,000 g/mol. In addition, the type of the polyol
is not particularly limited, but may be preferably one or more
selected from the group consisting of polyethylene glycol polyol,
polycarprolactone polyol, polyester polyol, polyether polyol,
polyacryl polyol, and polycarbonate polyoldiol. Preferably, more
specific examples of the polyol include 1,4-butanediol, diethylene
glycol, dipropylene glycol, polyalkylene glycol having an alkyl of
1 to 5 carbon atoms, and polyalkylene ether polyol. The
polyalkylene ether polyol may be one or more selected from the
group consisting of polytetramethylene ether glycol,
poly(oxytetramethylene)ether glycol, poly(oxytetraethylene)ether
glycol, poly(oxy-1,2-propylene)ether glycol, and
poly(oxy-1,2-butylene)ether glycol.
According to one embodiment of the present invention, the
polyisocyanate may have a number average molecular weight of
approximately 500 to approximately 50,000 g/mol. In addition, the
type of the polyisocyanate is not particularly limited, but is
preferably a polymer polymerized from aliphatic and aromatic
isocyanates. More specific examples of the aliphatic diisocyanate
may include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene
diisocyanate, 1,4-cyclohexyl diisocyanate, isophorone diisocyanate,
or .alpha.,.alpha.-xylylene diisocyanate. Examples of the aromatic
polyisocyanate may include 4,4'-dimethylmethane diisocyante,
1,3-phenylene diisocyanate or toluene diisocyanate. In addition,
polyisocyanate polymerized from dimers or trimers of the above
described diisocyanates may be used.
The above described components included in the thermosetting
prepolymer composition are crosslinked with each other by
thermosetting to form a thermosetting resin which confers high
hardness and processability on the coating layer.
According to one embodiment of the present invention, since the
thermosetting resin formed by thermosetting of the thermosetting
prepolymer composition, in addition to the crosslinked copolymer
polymerized by photo-irradiation, may be included, a setting
shrinkage or curl phenomenon in which a substrate is rolled up
together with the coating layer during photocuring can be
prevented. The curling phenomenon is a phenomenon in which the edge
or the like of a planar film is curvilinearly warped or rolled up
when the planar film is spread on a flat plate, and this curling
phenomenon occurs when acrylate is contracted during photocuring by
ultraviolet irradiation.
The plastic film must be improved in surface hardness to a degree
high enough to substitute for glass. Basically, the coating layer
is required to have a predetermined thickness, in order to improve
hardness of the plastic film. However, a thicker coating layer is
more prone to setting shrinkage which leads to increased curling
and decreased adhesiveness, and rolling up of the plastic film. In
this regard, a planarization process of the support substrate may
be additionally employed. Undesirably, the coating layer is likely
to crack during planarization. Accordingly, it is difficult to
prepare a plastic film which is high enough in hardness to
substitute for glass, without a decrease in physical properties of
the film.
According to one embodiment of the present invention, the presence
of the thermosetting resin in addition to the crosslinked copolymer
allows the plastic film to maintain high hardness and to prevent
photocuring-induced curling. In addition, toughness of the film is
improved to increase processability thereof. Hence, physical
properties of the plastic film can be further reinforced.
According to one embodiment of the present invention, the
thermosetting prepolymer composition may further include a catalyst
for promoting a thermosetting reaction. So long as it is known to
promote the condensation of the thermosetting prepolymer
composition, any catalyst may be available without limitations
thereto. In detail, the catalyst may be one or more selected from
the group consisting of dibutyltindilaurate (DBTDL), zinc octoate,
iron acetyl acetonate, N,N-dimethyl ethanolamine, and triethylene
diamine. These catalysts may be used alone or in combination of two
or more thereof.
According to one embodiment of the present invention, the
crosslinked copolymer and the thermosetting resin may be included
at a weight ratio of approximately 1:0.01 to approximately 1:3, or
approximately 1:0.1 to approximately 1:2, or approximately 1:0.1 to
approximately 1:1.5, or approximately 1:0.1 to approximately 1:1.2.
When the crosslinked copolymer and the thermosetting resin are
included in the above range, a plastic film having excellent
processability while maintaining high hardness can be provided.
According to one embodiment of the present invention, when the
coating layer further include the thermosetting resin,
approximately 40 to approximately 80 parts by weight of the
crosslinked copolymer, approximately 5 to approximately 50 parts by
weight of the thermosetting resin, and approximately 5 to
approximately 40 parts by weight of the inorganic fine particle may
be included, based on 100 parts by weight of the coating layer.
When used in such amounts, the thermosetting resin can endow the
plastic film with good physical properties such as high hardness
and high processability.
When the coating layer of the plastic film of the present invention
further includes the thermosetting resin in addition to the
crosslinked copolymer, they may form an interpenetrating polymer
network (IPN) structure.
As used herein, the `IPN structure` means the co-existence of two
or more crosslinked structures within the coating layer, as
exemplified by the first crosslinked structure constructed by the
photocuring of the tri- to hexafunctional acrylate-based monomer
and the caprolactone group-containing multifunctional
acrylate-based compound and the additional second crosslinked
structure constructed by the thermosetting of the thermosetting
prepolymer composition, respectively. Therefore, the plastic film
of the present invention may have an IPN structure in which two or
more crosslinked structures are entangled with each other within
the coating layer.
According to the present invention, the IPN structure may be
constructed by subjecting a coating composition containing both a
photocurable monomer and a thermosetting prepolymer composition to
photocuring and thermosetting reactions. That is, photocuring and
thermosetting are conducted on the coating composition sequentially
or simultaneously to allow the photocured and thermoset products to
be crosslinked to each other. Hence, the coating layer of the
present invention contains an IPN structure including both a first
crosslinked structure induced by photocuring the tri- to
hexafunctional acrylate-based monomer and the caprolactone
group-containing multifunctional acrylate-based compound; and a
second crosslinked structure induced by thermosetting the
thermosetting prepolymer composition.
According to one embodiment of the present invention, the coating
layer may be applied to a thickness of 50 .mu.m or more, for
example, approximately 50 to approximately 300 .mu.m, or
approximately 50 to approximately 200 .mu.m, or approximately 50 to
approximately 150 .mu.m, or approximately 70 to approximately 150
.mu.m.
Meanwhile, the coating layer may further include an additive
typically used in the art to which the present invention pertains,
such as a surfactant, a yellowing inhibitor, a leveling agent, an
antifouling agent or the like, in addition to the above described
crosslinked copolymer, thermosetting resin and inorganic fine
particle. Here, its content may be variously adjusted to the degree
that the physical properties of the plastic film of the present
invention are not degraded. Its content is not particularly
limited, but, for example, ranges from approximately 0.1 to
approximately 10 parts by weight, based on 100 parts by weight of
the coating layer.
According to one embodiment of the present invention, for example,
the coating layer may include a surfactant as an additive. The
surfactant may be a mono- or bi-functional fluorine acrylate, a
fluorine surfactant, or a silicon surfactant. In this regard, the
surfactant may be contained in a dispersed or crosslinked form in
the crosslinked copolymer. Further, a yellowing inhibitor may be
included as an additive. The yellowing inhibitor may be a
benzophenone compound, a benzotriazole compound or the like.
The coating layer may be formed by applying the coating composition
including the tri- to hexafunctional acrylate-based monomer, the
caprolactone group-containing multifunctional acrylate-based
compound, a photoinitiator, the inorganic fine particle, an organic
solvent, and optionally, the thermosetting prepolymer composition,
an additive, etc. onto the support substrate, and then photocuring
it.
The photoinitiator may be exemplified by
1-hydroxy-cyclohexyl-phenyl ketone,
2-hydroxy-2-methyl-1-phenyl-1-propanone,
2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone,
methylbenzoylformate,
.alpha.,.alpha.-dimethoxy-.alpha.-phenylacetophenone,
2-benzoyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone,
2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone
diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, or
bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, but is not
limited thereto. In addition, it may be commercially available
under the trade name of, for example, Irgacure 184, Irgacure 500,
Irgacure 651, Irgacure 369, Irgacure 907, Darocur 1173, Darocur
MBF, Irgacure 819, Darocur TPO, Irgacure 907, Esacure KIP 100F,
etc. These photoinitiators may be used alone or in combination of
two or more thereof.
The organic solvent may be an alcohol solvent such as methanol,
ethanol, isopropyl alcohol, and butanol; an alkoxy alcohol solvent
such as 2-methoxyethanol, 2-ethoxyethanol, and
1-methoxy-2-propanol; a ketone solvent such as acetone,
methylethylketone, methylisobutyl ketone, methylpropyl ketone, and
cyclohexanone; an ether solvent such as propylene glycol
monopropylether, propyleneglycol monomethyl ether, ethylene glycol
monethylether, ethyleneglycol monopropylether,
ethyleneglycolmonobutylether, diethyleneglycolmonomethylether,
diethylglycolmonoethyl ether, diethylglycolmonopropylether,
diethylglycolmonobutylether, diethyleneglycol-2-ethylhexyl ether;
an aromatic solvent such as benzene, toluene, and xylene; and they
may be used alone or in combination thereof.
In the coating composition, the organic solvent may be used in such
an amount that the weight ratio of the solid component to the
organic solvent ranges from approximately 70:30 to approximately
99:1, based on the solid component including the tri- to
hexafunctional acrylate-based monomer, the caprolactone
group-containing multifunctional acrylate-based compound, the
photoinitiator, the inorganic fine particle, the thermosetting
prepolymer composition, and other additive.
According to one embodiment of the present invention, the coating
layer may be formed only on one side of the support substrate.
According to another embodiment of the present invention, the
coating layer may be formed on both sides of the support
substrate.
When the coating layer is formed on both sides of the support
substrate, the coating composition may be applied onto the front
and back sides of the support substrate and cured in a sequential
or simultaneous manner. At this time, after application of the
coating composition, a process of drying the coating composition at
a predetermined temperature may be further carried out, in order to
evaporate the solvent and to form a planar film.
According to one embodiment of the present invention, the coating
composition including the above described components is applied
onto one side of the support substrate, and then photocured to form
the first coating layer.
When the first coating layer is formed using the first coating
composition, a typical method used in the art to which the present
invention pertains may be used. For example, the first coating
composition including the above described components is first
applied onto one side of the support substrate. At this time, the
method of applying the first coating composition is not
particularly limited, so long as it is used in the art to which the
present invention pertains. For example, bar coating, knife
coating, roll coating, blade coating, die coating, micro-gravure
coating, comma coating, slot die coating, lip coating, solution
casting or the like may be used.
Next, the first coating composition thus applied is photocured with
UV radiation to form the first coating layer.
The UV radiation may be emitted, for example, at a dose of
approximately 20 to approximately 600 mJ/cm.sup.2, or approximately
50 to approximately 500 mJ/cm.sup.2. The light source of UV
radiation is not particularly limited, so long as it is used in the
art to which the present invention pertains. For example, a
high-pressure mercury lamp, a metal halide lamp, a black light
fluorescent lamp or the like may be used. The photocuring step may
be carried out by irradiating UV light at the above dose for
approximately 30 seconds to approximately 15 minutes, or for
approximately 1 minute to approximately 10 minutes.
After completely cured, the first coating layer may have a
thickness of approximately 50 to approximately 300 .mu.m, or
approximately 50 to approximately 200 .mu.m, or approximately 50 to
approximately 150 .mu.m, or approximately 70 to approximately 150
.mu.m.
In this regard, according to one embodiment of the present
invention, the first coating composition applied onto one side of
the support substrate may be not completely cured at one time, but
partially cured to the degree that the photocurable functional
groups of the tri- to hexafunctional acrylate-based monomer and the
caprolactone group-containing multifunctional acrylate-based
compound contained in the first coating composition are partially
cured, for example, by approximately 30 to 60 mol %, or by
approximately 40 to 50 mol %. Therefore, the setting shrinkage of
the first coating composition is further reduced, conferring
excellent physical and optical properties as well as high hardness
on the plastic film without generating curls or cracks. Then, in
the after-mentioned step of curing the second coating composition
applied onto the back side of the supporting substrate, the
remaining first coating composition is cured, and thus, the curl
which is generated in the step of curing the first coating
composition is counterbalanced to afford a flat plastic film.
Next, the second coating composition including the above described
components is applied onto the other side, that is, the back side
of the support substrate. In this regard, the first and the second
coating compositions are the same as the above described coating
composition and are just terminologically discriminated for
application to opposite respective sides of the substrate.
Next, the second coating composition thus applied is photocured by
UV irradiation to form a second coating layer. In this regard, in
the step of photocuring the second coating composition, UV light is
irradiated to a surface opposite to that coated with the first
coating composition. Thus, the curl which may be generated by
setting shrinkage of the first coating composition is
counterbalanced to afford a flat plastic film. No additional
flattening processes are thus needed.
The UV radiation may be emitted, for example, at a dose of
approximately 20 to approximately 600 mJ/cm.sup.2, or approximately
50 to approximately 500 mJ/cm.sup.2. The light source of UV
radiation is not particularly limited, so long as it is used in the
art to which the present invention pertains. For example, a
high-pressure mercury lamp, a metal halide lamp, a black light
fluorescent lamp or the like may be used. The photocuring step may
be carried out with the above dose for approximately 30 seconds to
approximately 15 minutes, or for approximately 1 minute to
approximately 10 minutes.
After completely cured, the second coating layer may have a
thickness of approximately 50 to approximately 300 .mu.m, or
approximately 50 to approximately 200 .mu.m, or approximately 50 to
approximately 150 .mu.m, or approximately 70 to approximately 150
.mu.m.
According to one embodiment of the present invention, if the
coating composition further includes the thermosetting prepolymer
composition, the coating layer is formed by photocuring and
thermosetting. More specifically, the first coating composition is
first applied onto one side of the support substrate and
photocured, and then thermoset by heating it to a predetermined
temperature, after which a second coating composition is
subsequently applied to the other side, that is, the back side of
the substrate, and photocured, and then thermoset by heating it to
a predetermined temperature. In this regard, the first and the
second coating compositions are the same as the above described
coating composition and are just terminologically discriminated for
application to opposite respective sides of the substrate. With
regard to the order of photocuring and thermosetting, the
thermosetting may be first carried out, followed by photocuring, or
the photocuring may be first carried out, followed by
thermosetting. Preferably, the photocuring is first carried out,
followed by thermosetting to form a high-hardness plastic film with
higher processability.
As the thickness of the coating layer is increased, UV light does
not sufficiently reach the bottom of the coating layer, causing a
problem of incomplete curing of the coating layer. According to the
present invention, the curing of the thermosetting prepolymer
composition under both heat and UV can compensate for the
insufficient photocuring which might occur, thereby reinforcing the
hardness and physical properties of the coating layer. In addition,
the IPN structure including the first crosslinked structure
constructed by photocuring and the additional second crosslinked
structure constructed by thermosetting the thermosetting prepolymer
composition guarantees that the film has both high hardness and
processability.
The thermosetting for curing the thermosetting prepolymer
composition may be optionally carried out once or more times before
and/or after UV irradiation for photocuring. The thermosetting may
be achieved by heating at approximately 60 to approximately
140.degree. C., at approximately 80 to approximately 130.degree.
C., or at approximately 80 to approximately 120.degree. C. for
approximately 1 minute to approximately 1 hour, or for
approximately 2 minutes to approximately 30 minutes.
For use as a cover for mobile terminals or tablet PCs, it is
important that the plastic film must have hardness or impact
resistance elevated sufficiently to be a substitute for glass. Even
when formed at a high thickness on the substrate, the coating layer
according to the present invention is less prone to curling or
cracking, and imparts the plastic film with high transparency,
impact resistance, and self-healing capability.
The plastic film according to the present invention exhibits
excellent high hardness, scratch resistance, self-healing
capability, high transparency, durability, light resistance, light
transmittance or the like.
The plastic film of the present invention exhibits superiority in
terms of impact resistance, so that it can be used as a substitute
for glass. For example, the plastic film of the present invention
may not crack even after a steel bead weighing 22 g is freely
dropped ten times from a height of 50 cm thereto.
Further, the plastic film of the present invention may have a
pencil hardness of 6H or more, 7H or more, or 8H or more under a
load of 1 kg.
Further, the plastic film of the present invention exhibits
self-healing capability for recovery of the surface of the coating
layer within 30 seconds or 25 seconds after being rubbed with a
copper brush.
Further, the plastic film of the present invention may have a light
transmittance of 92% or more, and a haze of 1.0% or less, 0.5% or
less, or 0.4% or less.
Furthermore, the plastic film of the present invention may have an
initial color b* (b* defined by the CIE 1976 L*a*b* color space) of
1.0 or less. After the coating film is exposed to UVB under an
ultraviolet lamp for 72 hours or more, it may have a color b* value
which differs from the pre-exposed color b* value by 0.5 or less,
or by 0.4 or less.
Further, when the plastic film of the present invention is disposed
on a plane after exposure to a temperature of 50.degree. C. or
higher at a humidity of 80% or higher for 70 hours, the maximum
distance at which each edge or side of the plastic film is spaced
apart from the plane may be approximately 1.0 mm or less,
approximately 0.6 mm or less, or approximately 0.3 mm or less. More
particularly, when the plastic film is disposed on a plane after
exposure to a temperature of 50.degree. C. to 90.degree. C. at a
humidity of 80% to 90% for 70 to 100 hrs, each edge or side of the
plastic film is spaced apart from the plane by approximately 1.0 mm
or less, approximately 0.6 mm or less, or approximately 0.3 mm or
less, maximally.
Further, when the coating composition of the present invention
further includes the thermosetting prepolymer composition, and a
support substrate piece with dimensions of 10 cm.times.10 cm,
obtained by applying the coating composition to one side of the
support substrate, and curing under light and heat, is placed on a
flat plane, a maximal distance at which each edge or side is apart
from the plane may be 3 cm or less, or 2.5 cm or less, or 2.0 cm or
less.
As described above, the plastic film of the present invention
exhibits high hardness, impact resistance, self-healing property,
scratch resistance, high transparency, durability, light
resistance, high light transmittance or the like, and thus can be
applied to various fields. For example, the plastic film of the
present invention can be used in touch panels of mobile terminals,
smart phones or tablet PCs, and cover or device panels of various
displays as an alternative to a cover plate made of glass or
reinforced glass.
Hereinafter, the actions and effects of the present invention will
be described in more detail with reference to the specific
examples. However, these examples are for illustrative purposes
only, and the scope of the invention is not intended to be limited
by these examples.
EXAMPLE
Preparation Example 1: Preparation of Caprolactone Group-Containing
Multifunctional Acrylate-Based Compound
50 g of a caprolactone-grafted polyrotaxane polymer [A1000,
Advanced Soft Material Inc.] was introduced into a reactor, and
then 4.53 g of Karenz-AOI [2-acryloylethyl isocyanate, Showadenko
K.K.], 20 mg of dibutyltin dilaurate [DBTDL, Merck & Co, Inc.],
110 mg of hydroquinone monomethylene ether, and 315 g of
methylethylketone were added thereto and allowed to react at
70.degree. C. for 5 hours, so as to obtain a polyrotaxane polymer
containing cyclodextrin, to which a polycaprolactone group having
an acrylate-based compound at the end binds, as a macrocycle.
The polyrotaxane polymer thus obtained had a weight average
molecular weight of 600,000 g/mol and an elongation of 20% as
measured according to ASTM D638.
Preparation Example 2: Preparation of Thermosetting Prepolymer
Composition
To a jacket reactor were placed 50 g of methylethyl ketone and 50 g
of cyclohexanone, and then 70 g of polyurethane Estane 5701.RTM.
(Noveon, polyurethane containing Bronsted salt, number average
molecular weight of 40,000), followed by stirring for 2 hours at
80.degree. C.
Afterward, 14 g of polytetramethyleneetherglycol (Terathane
1000.RTM., Mw=1000, Sigma Aldrich), 1.5 g of 1,4-butanediol, and 17
g of a polyester polyol resin (dispersed in n-butyl acetate,
Desmophen 670BA.RTM., Bayer) were added to the reactor, and stirred
at room temperature for 30 minutes. Subsequently, 124 g of a cyclic
polyisocyanate (blocked with MEKO, Vestant B 1358A.RTM., Degusa),
0.3 g of dibutyltin dilaurate (DBTDL), and 1.2 g of Tego 410.RTM.
and 1.2 g of Tego 450.RTM. as additives, which are both fluidity
improvers, were introduced into the reactor, followed by stirring
to the homogeneity to afford a thermosetting prepolymer composition
with 70% of the solid content including the polyester-based
polyurethane oligomer, polyol and polyisocyanate.
Example 1
A coating composition was prepared by mixing 9 g of
silica-dipentaerythritol hexaacrylate (DPHA) composite in which 40%
by weight of nano-silica with a diameter of 20.about.30 nm was
dispersed (3.6 g of silica, 5.4 g of DPHA), 1.4 g of polyrotaxane
of Preparation Example 1, 0.2 g of a photoinitiator (brand name:
Darocur TPO), 0.1 g of a benzotriazole yellowing inhibitor (brand
name: Tinuvin 400), and 0.05 g of a fluorine surfactant (brand
name: FC4430) and 1 g of methylethylketone.
The coating composition was applied to a PET support substrate with
a size of 15 cm.times.20 cm and a thickness of 188 .mu.m, followed
by subjecting the composition to photocuring by irradiating UV
light of 280.about.350 nm using a black light fluorescent lamp so
as to form a first coating layer.
The coating composition was applied to the back side of the support
substrate, followed by subjecting the composition to photocuring by
irradiating UV light of 280.about.350 nm using the black light
fluorescent lamp so as to form a second coating layer. Thus, a
plastic film was fabricated. After completion of the curing, each
of the first and second coating layers formed on both sides of the
substrate had a thickness of 100 .mu.m.
Example 2
A plastic film was fabricated in the same manner as in Example 1,
except that 2 g of the polyrotaxane of Preparation Example 1 was
used instead of 1.4 g thereof in Example 1.
Example 3
A plastic film was fabricated in the same manner as in Example 1,
except that 9 g of silica-trimethylolpropane triacrylate (TMPTA)
composite in which 40% by weight of nano-silica with a diameter of
20.about.30 nm was dispersed (3.6 g of silica, 5.4 g of TMPTA) was
used instead of 9 g of the silica-DPHA composite in Example 1.
Example 4
A first coating composition was prepared by mixing 2.0 g of the
thermosetting prepolymer composition of Preparation Example 2, 9 g
of silica-dipentaerythritol hexaacrylate (DPHA) composite in which
40% by weight of nano-silica with a diameter of 20.about.30 nm was
dispersed (3.6 g of silica, 5.4 g of DPHA), 1.4 g of polyrotaxane
of Preparation Example 1, 0.2 g of a photoinitiator (brand name:
Darocur TPO), 0.1 g of a benzotriazole yellowing inhibitor (brand
name: Tinuvin 400), and 0.05 g of a fluorine surfactant (brand
name: FC4430). A second coating composition was also prepared in
the same manner.
The first coating composition was applied to a PET support
substrate with a size of 15 cm.times.20 cm and a thickness of 188
.mu.m, followed by subjecting the composition to photocuring by
irradiating UV light of 280.about.350 nm using a black light
fluorescent lamp and then to thermosetting at 130.degree. C. for 30
minutes to form a first coating layer.
The second coating composition was applied to the back side of the
support substrate, followed by subjecting the composition to
photocuring by irradiating UV light of 280.about.350 nm using the
black light fluorescent lamp and then to thermosetting at
130.degree. C. for 30 minutes to form a second coating layer. After
completion of the curing, each of the first and second coating
layers formed on both sides of the substrate had a thickness of 100
.mu.m.
Example 5
A plastic film was fabricated in the same manner as in Example 4,
except that 3.6 g of the thermosetting prepolymer composition of
Preparation Example 2 was used instead of 2.0 g thereof in Example
4.
Example 6
A plastic film was fabricated in the same manner as in Example 4,
except that 9 g of silica-trimethylolpropane triacrylate (TMPTA)
composite in which 40% by weight of nano-silica with a diameter of
20.about.30 nm was dispersed (3.6 g of silica, 5.4 g of TMPTA) was
used instead of 9 g of the silica-DPHA composite in Example 4.
Example 7
A plastic film was fabricated in the same manner as in Example 4,
except that 2 g of the polyrotaxane of Preparation Example 1 was
used instead of 1.4 g thereof in Example 4.
Example 8
A plastic film was fabricated in the same manner as in Example 4,
except that 9.0 g of the thermosetting prepolymer composition of
Preparation Example 2 was used instead of 2.0 g thereof in Example
4.
Comparative Example 1
A plastic film was fabricated in the same manner as in Example 1,
except that 10 g of the silica-DPHA composite was used (4 g of
silica, 6 g of DPHA) instead of 9 g of silica-DPHA composite and
the polyrotaxane of Preparation Example 1 was not used in Example
1.
Comparative Example 2
A plastic film was fabricated in the same manner as in Example 1,
except that 1.0 g of the polyrotaxane of Preparation Example 1 was
used instead of 1.4 g thereof in Example 1.
Comparative Example 3
A plastic film was fabricated in the same manner as in Example 4,
except that 10 g of the DPHA composite was used (4 g of silica, 6 g
of DPHA) instead of 9 g of silica-DPHA composite and the
polyrotaxane of Preparation Example 1 was not used in Example
4.
Comparative Example 4
A plastic film was fabricated in the same manner as in Example 4,
except that 1.0 g of the polyrotaxane of Preparation Example 1 was
used instead of 1.4 g thereof in Example 4.
Main components of the compositions used in Examples 1 to 8 and
Comparative Examples 1 to 4 are summarized in Table 1, below.
TABLE-US-00001 TABLE 1 Type and con- Caprolactone tent of tri-
group-containing to hexafunc- multifunctional Thermosetting tional
acrylate- acrylate-based Silica prepolymer based monomer compound
(unit: composition (unit: g) (unit: g) g) (unit: g) Example 1 DPHA,
5.4 1.4 3.6 -- Example 2 DPHA, 5.4 2 3.6 -- Example 3 TMPTA, 5.4
1.4 3.6 -- Example 4 DPHA, 5.4 1.4 3.6 2.0 (solid con- tent:
approxi- mately 1.4 g) Example 5 DPHA, 5.4 1.4 3.6 3.6 (solid con-
tent: approxi- mately 2.5 g) Example 6 TMPTA, 5.4 1.4 3.6 2.0
(solid con- tent: approxi- mately 1.4 g) Example 7 DPHA, 5.4 2 3.6
2.0 (solid con- tent: approxi- mately 1.4 g) Example 8 DPHA, 5.4
1.4 3.6 9.0 (solid con- tent: approxi- mately 6.3 g) Comparative
DPHA, 6 -- 4 Example 1 Comparative DPHA, 5.4 1.0 3.6 Example 2
Comparative DPHA, 6 -- 4 2.0 (solid con- Example 3 tent: 1.4 g)
Comparative DPHA, 5.4 1.0 3.6 2.0 (solid con- Example 4 tent:
approxi- mately 1.4 g)
Experimental Example
<Measurement Methods>
1) Pencil Hardness
Hardness was measured using a pencil hardness tester under a load
of 1.0 kg according to Measurement Standard JIS K5400 three times,
and then the hardness at which no scratches appeared was
determined.
2) Self-Healing Capability
A time to recover from a scratch after rubbing the surface of a
coating layer with a copper brush under a load of 1 kg once was
measured.
3) Light Resistance
Differences in color b* value were measured before and after
exposure to UVB in a UV lamp for 72 hours or longer.
4) Transmittance and Haze
Transmittance and haze were measured using a spectrophotometer
(brand name: COH-400).
5) Curl Property
After the formation of the first coating layer, the film was cut
into a piece with dimensions of 10 cm.times.10 cm and placed on a
flat plane. A maximal distance at which each edge or side was apart
from the plane was measured.
6) Cylindrical Bending Test
Each of the plastic films was wound on a cylindrical mandrel having
a diameter of 3 cm, and cracking occurrence was examined. When the
plastic film was not cracked, it was evaluated as OK. If the
plastic film was cracked, it was evaluated as X.
7) Impact Resistance
The impact resistance of each of the plastic films was evaluated by
determining whether each of the plastic films was cracked when 22 g
of a steel ball was dropped 10 times thereon from a height of 50
cm. Each of the plastic films was evaluated as OK when it was not
cracked, and as X when cracked.
The results of measuring the physical properties are summarized in
Tables 2 and 3, below.
TABLE-US-00002 TABLE 2 Example Example Example Example Example
Example Example Example 1 2 3 4 5 6 7 8 Pencil hardness 7H 6H 6H 8H
6H 6H 6H 6H Self-healing 25 sec 10 sec 25 sec 25 sec 20 sec 25 sec
15 sec 20 sec capability Light resistance 0.20 0.24 0.15 0.21 0.23
0.18 0.28 0.16 Transmittance 92.1 91.9 92.3 92.3 92.0 91.9 92.0
92.5 Haze 0.3 0.2 0.3 0.3 0.2 0.3 0.4 0.4 Bending test OK OK OK OK
OK OK OK OK Curl property 0.3 mm 0.4 mm 0.2 mm 0.3 mm 0.4 mm 0.3 mm
0.2 mm 0.1 mm Impact resistance OK OK OK OK OK OK OK OK
TABLE-US-00003 TABLE 3 Comparative Comparative Comparative
Comparative Example 1 Example 2 Example 3 Example 4 Pencil hardness
9H 8H 8H 6H Self-healing No recovery 2 min No recovery 2 min
capability Light resistance 0.35 0.38 0.25 0.25 Transmittance 92.0
92.1 92.1 92.3 Haze 0.4 0.3 0.2 0.3 Bending test X OK OK OK Curl
property 0.5 mm 0.4 mm 0.3 mm 0.2 mm Impact X OK X OK
resistance
As shown in Tables 2 and 3 above, all of the plastic films of
Examples 1 to 8 of the present invention were found to have good
physical properties, particularly, to exhibit self-healing
capability for recovery of the surface within 30 seconds after
being rubbed with a copper brush.
* * * * *